This invention relates to an improved method and system for bearer path optimization through a succession of border gateways in an Internet Multimedia Subsystem (IMS) network. More particularly, this invention relates to a method and apparatus for identifying alternative end-to-end media paths through Internet Protocol (IP) realms using substitute Session Description Protocol (SDP) parameters.
While the invention is particularly directed towards IP multimedia bearer path optimization and thus will be described with specific reference thereto, it will be appreciated that the invention may have other usefulness in other fields and applications. For example, this invention may be used in a variety of data transfer systems and methods including other systems and methods that utilize the SDP and the SDP offer/answer model. This method and system will allow Session Initiation Protocol (SIP) based networks to bypass one or more border gateways that would otherwise be included in the media path.
By way of background, the IMS/SIP based network is an internet protocol based network that supports many types of user equipment. This user equipment uses Voice over Internet Protocol (VoIP) and other methods to transfer data and voice in real time applications across the IP network. A SIP based network call has a call signaling path and a bearer path. The call signaling path handles call control data which is used to set-up, connect and process the call. The bearer path is the voice data connection over which a conversation takes place, and is also referred to as a multimedia session path or media path.
In IMS and other SIP-based networks, border gateways are deployed between IP realms defined by each network. Within an IP realm every IP endpoint is reachable from every other IP endpoint using a common IP address space. The border gateways provide security to the IP realm by limiting access to the IP endpoints within an IP realm. The media path associated with a multimedia stream may traverse an arbitrary number of IP realms along an end-to-end media path. When a border gateway has access to additional IP realms on the path, there is an opportunity to create a shorter media path.
Therefore, there is a need in the industry to allow for improved border gateway bypass procedures. There is further need in the industry to allow border gateway bypass procedures that require no additional signaling messages beyond what is needed for a single end-to-end Session Description Protocol (SDP) offer/answer transaction and that require no new procedures in session IP endpoints. There is a further need in the industry to allow border gateways to protectively manage security and aggregate bandwidth usage for all sessions. Finally, there is a need in the industry to supply an optimization procedure which shortens the route that a bearer path must take, thereby freeing resources of border gateways, reducing bearer traffic through IP networks, and minimizing end-to-end delay, thus improving Quality of Service (QoS).
The present invention contemplates a new and improved system and method that resolves the above-referenced difficulties and others.